Patterning device for patterning a substrate with patterning cavities fed by service cavities

ABSTRACT

A patterning device comprises a patterning cavity which has an opening located at the surface of the patterning device within a transfer region, where a substrate during patterning comes into conformal contact with the patterning device. A service cavity is located in a service region of the patterning device and is connected to the patterning cavity, such that a patterning fluid is able to flow from the service cavity to the patterning cavity. A patterning method uses this device.

FIELD OF THE INVENTION

The present invention is directed towards patterning of a substrate. Itaims in particular at, but is not restricted to, the creation ofmicroscopically small patterns of the type used in micro-electronicse.g. semiconductor chips and micro-technology. More specifically, theinvention relates to the patterning of a substrate by using a patterningdevice, the pattern being materialized in the form of openings in atransfer region of the patterning device surface.

The invention relates also to the modification of the contactedsubstrate surface under the influence of fluids filled into or rinsedthrough the cavity.

The invention relates also to the controlled deposition of one ordifferent types of chemically defined bodies on predetermined areas ofthe contacted substrate surface.

The term "conformal contact" implies that the surface shapes of twomedia put on top of each other are similar to such an extent that fluidscan essentially not penetrate into the plane where the surfaces meeteach other. The term "fluid" refers to both liquids and gases. The fluidmay consist of several components such as a solution and of more thanone phase such as an emulsion or a suspension (slurry) of bodies in acarrier fluid.

With regard to the potential applications of the invention, thestructuring of materials used in microelectronics, in particular siliconwafers, is of central importance. Here, it may be possible to replacecertain lithographic processing steps by the patterning with apatterning device. In biotechnology, the controlled deposition ofchemically defined bodies (CDBs) may greatly profit from the presentinvention. As a CDB shall be understood as any object which consists ofone or more molecules whose chemical composition is at least partiallyknown at the external region of the body such that a preferentialorientation is chemically determinable. In particular, such CDBs may beligands or receptors which are chemically attractive to specificcomplementary receptors or ligands like keys that fit into specificlocks. In case of such single-molecular particles, the distinctionbetween solution and suspension becomes meaningless.

The fluids can react with the contacted substrate surface in variousways, resulting in dissolution or chemical modification of substratematerial, or in precipitation of a new material. The resultingstructures are restricted to the exposed areas of the contactedsubstrate surface, hence replicate the original pattern. Afterseparation from the patterning device, the substrates can be furtherprocessed, e.g. by lithographic methods, using deposited layers asmasks, or be employed as secondary stamps.

BACKGROUND OF THE INVENTION

The structuring of surfaces according to predetermined patterns is anelementary step in any device-manufacturing process. Precision, speedand cost of the structuring processes frequently are decisive factorsfor success or failure of a product. The development ofmicroelectronics, microbiology, and microtechnology in general raisedthese needs enormously, generating ever increasing requirements forsmaller structures, larger scale integration, and lower cost.

The classical patterning techniques used in microtechnology are photo-and electron beam lithography. Photolithography is a fast, efficientparallel process. Its principal problem is the diffraction limit whichrestricts the minimum structural dimensions to about one half to onequarter of the light wavelength. To cope with the shrinking dimensionsof microtechnical structures, imaging systems for shorter and shorterwavelengths were developed in recent years. Due to a number of basiclimitations, the ultimate limits of conventional optical lithographywill be of the order of 100 nm. These dimensions will be reached soon.Near-field optical lithography is not bound to the diffraction limit andtherefore suitable for the generation of even smaller structures. Thismethod, however, still is in a very early state; its potential forindustrial application cannot be estimated yet.

Electron beam lithography is the present day's preferred solution forthe generation of structures with very small dimensions. As a serial,direct writing process, however, it becomes slower and slower withincreasing complexity of the patterns to be transferred. For thisreason, electron beam lithography has been used mainly in maskfabrication so far and not in the mass production of semiconductorchips. Ion beam lithography operates on similar principles as electronbeam lithography but is far less established because of ion implantationand other disadvantageous effects.

A basic feature of optical and electron lithography is the use of anoverlay, typically an organic polymer, that serves as the base forpattern formation on an underlying substrate. The overlay is formed onthe substrate by homogenous deposition. Evaporation or spin-coating froman organic solvent provides a continuous film on the substrate. Exposureof the overlay to radiation (optical, electron or ion) causes localizedchanges in its chemistry permitting differential dissolution of theoverlay and opening up windows in the film onto the underlyingsubstrate. Patterning can then be affected by wet chemical or dryetching processes where the presence of the overlay provides a local,externally controlled physical mask to chemical reaction. Alternatively,material can be deposited onto the substrate through the windows in theoverlay by various methods such as evaporation, chemical vapor orsputter deposition, or galvanic techniques. These methods of patternformation are tremendously useful; nevertheless they have certainshortcomings: Several steps are required before pattern transfer iscomplete; dissolution of the overlay requires a development step thatexposes the whole system to organic solvents, plasmas or otherwisechemically harsh conditions. Here, bulk quantities of chemicals areconsumed even though only quite localized chemical reactions are needed,steps that are generally wasteful of the reagents. The use of physicalmasks means that when material is deposited through the mask much of itwill be unproductively directed onto the tops of the physical mask.Afterwards, where elimination of the externally controlled physical maskis needed, the conditions for this removal can be injurious to the newlyformed substrate, especially where fragile organic materials have beendeposited. Furthermore, the masking layer provided by the overlay is notreusable so that specialized equipment is required to form a new patternon an existing or subsequent substrate. Finally, irradiation used toform the pattern can damage the underlying substrate by the introductionof chemical or electronic disturbances in the region near the overlay.

In view of the increasing gap between the needs of industry and theexistence of foreseeable limitations of the established techniques, thedevelopment of alternatives is highly desirable. Stamping techniques,including embossing and gravure (intaglio printing) are promisingcandidates in this context. Ignored for many years in micro-technology,they recently began to attract renewed attention: It was demonstratedthat structures with very small dimensions, in some cases of less than100 nm in size, can be replicated by means of stamping techniques asdescribed, with regard to the use of self-assembled monolayers e.g. inthe article by A. Kumar, H. Biebuyck and G. M. Whitesides "PatterningSAMs: Applications in Materials Science", Langmuir 10, 1498 (1994) or byH. Biebuyck, N. B. Larsen, E. Delamarche and B. Michel in "LithographyBeyond Light", IBM Journal of Research and Development 41, 159-170(1997), with regard to embossing e.g. by Y. Chou, P. R. Krauss and P. J.Renstrom "Imprint of Sub-25 nm vias and Trenches in Polymers", Appl.Phys. Lett. 67, 3114-3116 (1995), and with regard to intaglio techniquese.g. by E. Kim, Y. Xia and G. M. Whitesides "Polymer MicrostructuresFormed by Molding in Capillaries", Nature, 376, 581-583 (1995) and by E.Delamarche, A. Bernard, H. Schmid, B. Michel and H. Biebuyck "PatternedDelivery of Immunoglobins to Surfaces Using Microfluidic Networks",Science 779-781 (1997). Intaglio techniques, commonly known fromgravure, exploit capillary attachment of inks to the cavities of apatterning at the surface of a patterning device. When pressed againstthe inked patterning device, the paper penetrates the cavities slightlyand draws out the ink.

In microtechnology, the substrate to be structured neither is porous norflexible in general. Furthermore, the desired modification does notnecessarily involve the deposition of an ink. It is possible, however,to conceive pattern transfer devices and methods on the basis ofintaglio printing techniques which are not restricted to those modes ofoperation and open interesting alternatives to the conventionallithography while avoiding some of the disadvantages mentioned before.

In the publication by S.P.A. Fodor et al. "Light-directed, spatiallyaddressable parallel chemical synthesis", a method is described whichcombines solid-phase chemistry, photolabile protecting groups andphotolithography to yield a highly diverse set of chemical products.Binary masking yields 2^(n) compounds in n chemical steps. For eachstep, the test substrate has to be covered completely with materialcontaining one of the n starting materials. The resulting consumption ofstarting materials can become considerable if the cost of thesematerials is high. The method was used successfully in accessing geneticinformation with high-density DNA arrays as described in the articlewith the same title by M. Chee et al. which appeared in Science, Vol.274, 610-614, Oct. 25, 1996.

H. Biebuyck, E. Delamarche and B. Michel disclosed a method inInternational patent application PCT/IB96/00908 which allows controlleddeposition of CDBs by means of a stamping technique and mediated bylayers of complementary CDBs (C-CDBs). The CDBs and C-CDBs can bemolecules, macromolecules and/or other nanostructures. The proposedmethod is applicable on (C-)CDBs whose chemical composition is at leastpartially known at the external region of the body which allows todeposit them with a chemically determinable orientation, as is the casewith many molecules or macromolecules or materials or componentsderivatized on their surface to have a useful chemical asymmetry.Specifically, such (C-)CDBs may be organic molecules acting as ligandsor receptors for the respective complementary molecules.

Specifically, Biebuyck et al. suggest to use a stamping means forsimultaneous locally-separated deposition of different CDBs whose ridgesare "inked" with different types of C-CDBs. The stamping means then isdipped into a fluid which contains the CDBs to which the C-CDBs arecomplementary. After selective attachment of the CDBs, the stampingmeans is removed from the fluid and brought in contact with a substrate.The surface of the substrate is covered with an attachment means whichexerts strong adhesion on CDBs. The CDBs get attached and hencetransferred to the substrate surface in areas predetermined by thepattern of the stamping means. By this procedure, the orientation of theCDBs is guaranteed and the arising functionality is maximised.

In the patent application by Biebuyck et al., the step of inking thestamping means with different C-CDBs, which is a non-trivial one, wasleft unattended. The present invention provides a simple solution tothis problem and at the same time allows to generate in a single steppatterns formed by different C-CDBs.

In the above-mentioned publication by E. Delamarche, A. Bernard, H.Schmid, B. Michel and H. Biebuyck "Patterned Delivery of Immunoglobinsto Surfaces Using Microfluidic Networks", Science 779-781 (1997), theauthors describe the formation of a network of conduits at the interfaceof a substrate in contact with a printing plate made from an elastomer.The active transfer region of the printing plate is structured into apatterning in such a way that capillaries are formed which can be filledthrough openings arranged outside the transfer region. The capillariescan direct spatially chemical reactions between the surface of thesubstrate and ligands introduced by flow of aqueous, buffered solutionsthrough the network, immobilizing ligands, --like drugs, enzymes andimmunoglobins--all along the conduits by their covalent attachment tothe activated substrate. Release of the elastomer reveals a uniform andfunctional layer of the ligands in the image of the pattern molded inthe elastomer. Subsequent exposure of this substrate to a homogeneous orheterogeneous solution of receptors allows specific recognition andattachment of the receptors to the immobilized ligands with highresolution (sub-micron) and specificity.

SUMMARY OF THE INVENTION

A patterning device is proposed which has a transfer region whichcomprises a patterning structure which may consist of a plurality ofpatterning cavities. The patterning cavities may be connected to eachother and to link cavities. Furthermore, a service cavity is part of thepatterning device and is connected to at least one patterning cavity forsupplying the patterning cavity with a fluid. The link cavities bridgethe distances between separated patterning cavities or between apatterning cavity and a service cavity and may particularly serve forbuilding conduits that comprise several connected cavities but areindependent from each other. The service cavity lies mainly in a serviceregion of the patterning device which is outside the transfer region.

The patterning cavities get closed due to the intimate contact with thesubstrate surface onto which a pattern is to be transferred. Thecavities then become conduits which can be filled, rinsed, and/oremptied by fluid supply means attached to or integrated into the serviceregion. Depending on the kind of fluid, the pattern can be created ortransferred by dissolution or modification of the contacted substratesurface, or by precipitation of material from the fluid. Fillingdifferent conduits with different fluids simultaneously and/or the sameconduits in sequence allows one to build complexly structured patternson the contacted substrate surface. Use of such a patterned substrate asa secondary stamp enlarges the range of applications of this patterntransfer technique.

Also a patterning method is proposed which uses the patterning device.The device and method described are particularly suited for the transferof microscopically small patterns of the type used in micro-electronicse.g. semiconductor fabrication and micro-technology.

In the present invention, a patterning device comprises a certainregion, called transfer region, which comprises patterning cavitieswhich may be connected by auxiliary link cavities. Additionally, servicecavities are connected to the patterning cavities. When brought incontact with a substrate which is to be patterned, each cavity is closedto form a conduit which can be filled, rinsed, emptied, refilled etc.with one or more fluids without removal of the patterning device fromthe substrate. The transfer region of a patterning device may comprisemany cavities which form a conduit when in contact with the substrate.The network may include conduits of microscopically small dimensions.This is a first object of the present invention.

A second object of the invention is a method for patterning with such apatterning device a contacted substrate surface. Reactions between therespective fluids filled into the network and the exposed areas of thecontacted substrate surface can result in dissolution or modification ofsubstrate material as well as deposition of material from the fluids onthe substrate. The use of conduits with microscopically small dimensionsallows generating patterned structures of the size required inmicroelectronics and microtechnology in general.

A third object of the invention is the extension of these techniques tomore complex patterning schemes such as the use of an externallycontrolled physical influence, e.g. light, electric current, toinitiate, sustain, stop, and/or suppress the reaction between the fluidsand the substrate.

The invention according to one embodiment has the property that aconduit, comprising a patterning cavity and a service cavity is formedwhen conformal contact is made between the transfer region of thepatterning device and the substrate. This has the advantage that theconduit can be filled with a fluid during contact. The surface of thepatterning device can for this purpose be chosen to be flexible, e.g. bycomprising an elastomeric material.

The invention implies a capability to manipulate fluids in the conduitand to influence the reactions between these fluids and the exposedareas of the contacted substrate surface.

A small opening and an increasing width below has the advantage that theflow resistance in the conduits can be kept low even if the openings ofthe patterning cavities are very narrow and/or the conduits are verylong.

An embodiment comprising an integrated or external fluid supply means(pump, reservoir, valve etc.) has the advantage that the conduit,specifically the patterning cavity can be rinsed continuously, emptiedand/or refilled without removal of the patterning device from thecontacted substrate surface. Rinsing of the fluid s has the advantagethat their compositions vary much less due to material precipitation oruptake during the pattern transfer process than in case of a one-timefilling of the cavities. For applications which require a large varietyof different fluids to be filled into the conduit, the fluid supplymeans may consist of cartridges with rows of integrated fluid containerswhose valves can be plugged connected to matching rows of entranceservice cavities. This will allow efficient filling of large numbers ofconduits.

The cavity may be evacuated before filling or the medium occupying thecavities, for instance air, is driven out during filling by diffusionthrough the patterning device and/or substrate or through a secondservice cavity. The formation of a conduit has the advantage that thefluid is shielded from the influences of the environment while floatingthrough the cavity. In this way, pollution or changes in concentrationof the fluid due to evaporation can be avoided.

An embodiment with a good wettability in the conduit has the advantagethat the fluid is pulled into the conduit under the influence of wettingforces. The importance of this effect increases with decreasing crosssections of the conduit. It therefore facilitates the filling ofminiaturised conduits. Good wettability of the walls of the conduit incombination with poor wettability of the exterior surface of thetransfer region has the further advantage that the patterning cavityremains quasi-closed for a fluid even if the contact between contactedsubstrate surface and transfer region of the patterning device is lessthan perfect. It is possible, for instance, to make the wallshydrophilic and the exterior surfaces hydrophobic. This makes itenergetically favorable for an aqueous fluid to stay out of the smallcrevasses that might be left open between patterning device and thesubstrate to be patterned. As a result, the shape tolerance requirementsfor the transfer region of the patterning device respectively and thecontacted substrate surface can be relaxed.

Arranging the transfer region in a recess on one hand is a good meansfor achieving an automatic adjustment or alignment of the substraterelatively to the patterning device and on the other hand brings abigger flow resist to the fluid, when the fluid is able to penetrateinto the gap between the substrate and the patterning device. Dependingon the quality of the contact between the substrate and the patterningdevice it could be possible that the fluid to a certain extent flowsinto this gap and deposits some material on the substrate. One possiblesolution to remove such unwanted material could be a short removingprocess, such as etching, which due to a big difference in layerthickness does only insignificantly damage the pattern. This is howeverno solution for monolayer-forming reactions, where hence greatest careshould be taken to avoid such gap penetration by a very conformalcontact.

An embodiment with a transfer element and a bottom element has theadvantage that the patterning device can be optimized according todifferent design criteria simultaneously. It is possible, for instance,to make the bottom element of the patterning device conductive and thetransfer element insulating. It is also possible to use a stiff bottomelement which defines the overall shape of the patterning device and tocombine it with an elastomeric transfer element which provides shapeadaptability. In still another possible application, a UV-lighttransparent bottom element may be employed, which allows for localphoto-activation or passivation by an external UV light source.

An embodiment with one or more link cavities has the advantage thatpatterning cavities in separated parts of the transfer region can beconnected to form single or branched strings of cavities each of whichmay begin and/or end in a single service cavity. This allows thetransfer of complex patterns with a small number of service cavities. Itis possible, for instance, to have some patterning cavities of aparticular string be surrounded completely with patterning cavities froma different string. This is achieved by burying one or several linkcavities in the depth of the patterning device.

A method according to the invention allows modification of the exposedareas of a contacted substrate surface by chemical reactions with thefluid filled into the cavities. The reaction may result in dissolutionor chemical modification of the substrate material, or in deposition,physi- or chemisorption and/or growth of layers of new materials on topof the substrate. This has the advantage that the contacted substratesurface can be patterned in the shape of depressions, chemicallymodified regions, and/or elevations made up of new materials. The newmaterials may differ from that of the substrate or may be the same.

A method using an attachment means has the advantage that, mediated byan attachment means, material precipitated from the fluids can beattached to the exposed areas of the contacted substrate surface even ifthe untreated substrate surface was repelling to the material. Theattachment means furthermore may be chosen such that the adhesion isselective for certain materials, for instance certain classes of CDBs orC-CDBs. The attachment means thus can suppress the deposition ofunwanted materials contained in the fluids; it also can be useful forpurification of the fluids.

A method which uses the attachment means as orienting means has theadvantage that all CDBs, respectively C-CDBs are deposited with acertain, predetermined orientation which maximizes their functionality.

A method which uses different fluids in different conduits has theadvantage that differently structured patterns can be generated at thecontacted substrate surface simultaneously. It is possible, forinstance, that a first conduit is filled with a fluid from whichmaterial is precipitated, resulting in a first, elevated pattern, andanother conduit is filled with a corrosive, resulting in second,recessed pattern on the contacted substrate surface.

In another application, different types of C-CDBs, in particular ligandsor receptors may be deposited simultaneously on a contacted substratesurface. The substrate patterned in this way can be used as a test probefor the receptors and ligands, respectively, to which the C-CDBs arecomplementary. If the conduit of a first and a second patterning deviceconsist of n parallel channels each which are oriented orthogonal toeach other and if the two patterns are transferred sequentially to thesubstrate, then n² combinations of materials can be deposited.High-density DNA, protein or peptide arrays, useful for assaying, can begenerated effectively in this way. Also patterns can be generated whichare composed of several structures. It is possible, for instance, todeposit two layers on top of each other in the shape of the pattern byrinsing through the conduits two different fluids, one after the other,from which the two layers are precipitated, respectively. It is alsopossible to rinse a cleaning fluid in between in order to avoid mixingof the two precipitation generating fluids. Rinsing of two fluids inperiodic alternation allows the generation of superlattice-typepatterned layers by this method. In another application, the first fluidmight be corrosive, producing a pattern of grooves which might be filledup with a different material by precipitation from the second fluid. Themethod can also be used for separation and purification of CDBs in aprocess of selective affinity chromatography as described in "Guide toprotein purification", by Murray P. Deutscher, Academic Press, Vol. 182.This method is general and used extensively in the purification of smalland large molecules known in the chemical and biochemical fields.

A method where the reaction of the fluid with the substrate may beenabled or suppressed by externally controlled physical influence, e.g.by electrochemical or photochemical effects is more universal, sinceadditionally to the patterning scheme mechanically predetermined by thepatterning cavity dimensions, the selective control provides a schemewhich allows to vary the result. Thereby even a higher definition can beachieved, for instance when the control scheme represents the patterningscheme and is slightly shifted relatively to the patterning cavity. Forthe first example, an insulating transfer element and a conductivebottom element and substrate may be chosen. Application of voltagebetween bottom element and substrate allows convenient control of theelectrochemical modification; it is even possible to transfer certainparts of the pattern selectively by appropriate division of the bottomelement into mutually isolated electrodes. For the second example, thepatterning device and/or substrate may be fabricated from a transparentmaterial. A focused beam of light allows for photoactivation or-passivation, for instance of CDBs and/or C-CDBs in predeterminedsections of the exposed areas of the contacted substrate surface.

A method which uses the substrate as a secondary stamp allows theformation of a pattern on a target substrate in ways which cannot easilybe achieved by a single step pattern transfer process. CDBs, forinstance prefer to adhere to their complementary on a substrate throughtheir reactive ends. If such a substrate is used as intermediatesubstrate, the CDBs can be transferred to a third substrate, serving asthe target substrate, in the reverse, "backside up" orientation, wherethey can be fixed without interfering with the reactive end. Thisapproach maximizes the amount of correctly oriented CDBs on the targetsubstrate.

The method further is advantageous if the pattern transfer processrequires the usage of aggressive chemicals respectively and chemicallysensitive target substrates. In such a case, the intermediate substratecan be made from a material which is inert with respect to theaggressive chemical.

Besides microelectronics, biotechnology may profit in particular fromadvanced microstructuring techniques. Large numbers of different typesof CDBs can be deposited at predetermined positions of a substrate withthe help of the present invention. For instance, immobilizing ligands onsurfaces is a first step in many bioassays, a prerequisite in the designof bio-electronic devices, and valuable in certain combinatorialscreening strategies. Existing methods typically expose macroscopicareas of a substrate to milliliter quantities of solution to affectattachment of one type of molecule, sometimes using light andspecialized chemistries to carry out localized reactions.

The method is further advantageous in that it is highly conservativebecause the reagents can be recovered from the arrangement after havingbeen used for patterning the substrate.

DESCRIPTION OF THE DRAWINGS

Examples of the invention are depicted in the drawings and described indetail below by way of example. It is shown in

FIG. 1A shows a side view cut through a patterning device with emptycavities,

FIG. 1B shows a top view of the same patterning device,

FIG. 1C shows a side view cut through the same patterning device incontact with a substrate, the cavities being filled with fluids,

FIG. 2 shows a view in perspective of the same patterning device incontact with a substrate, the patterning device being connected to afluid supply means,

FIGS. 3A-G shows the states after different steps in the process ofpattern transfer by reaction of fluids with the substrate surface,

FIGS. 4A-C shows the states after different steps in the process ofpattern transfer by a reaction of a fluid with the substrate surfaceinduced by an externally controlled physical influence,

FIG. 5A shows a state in a process for manufacturing a test slide by theattachment of complementary chemically defined bodies (C-CDBs),

FIG. 5B shows a test slide with complementary chemically defined bodies(C-CDBs),

FIGS. 5C and 5D show the use of a test slide for the detection and/oraccumulation of chemically defined bodies (CDBs) to which the C-CDBs arecomplementary.

The figures are not shown in real dimensions for the sake of clarity,nor are the relations between the dimensions shown in a realistic scale.

DETAILED DESCRIPTION OF THE INVENTION

Out of the variety of opportunities for pattern transfer provided by thepresent invention, a number of exemplary embodiments and methods aredescribed hereinafter.

FIGS. 1A and 1B schematically show a patterning device, which is alsocalled printing plate 1, in a sidecut-view and a top view, respectively.At the top surface of the printing plate 1, a transfer region 10 and aservice region 11 can be distinguished. A first patterning cavity 12, asecond patterning cavity 13, a link cavity 14, a first service cavity 15and a second service cavity 16 together form a first string of cavities12, 13, 14, 15, and 16. The two patterning cavities 12 and 13 lieessentially in the transfer region 10 and are connected via the linkcavity 14. The first and second service cavity 15 and 16 respectivelyconnect the first and second patterning cavity 12, 13 with openings inthe service region 11.

A U-shaped patterning cavity 17, a third service cavity 18 and a fourthservice cavity 19 together form a second string of cavities 17, 18, and19. The U-shaped patterning cavity 17 lies mainly in the transfer region10. The third and fourth service cavity 18 and 19 respectively connectthe U-shaped patterning cavity 17 with openings in the service region11. The width at the opening of the U-shaped patterning cavity 17 isnarrower at the top than the width at its base. Hence, itscross-sectional area is increased compared to a cavity with straightside walls with the same width as the opening at the top.

The link cavity 14 is buried in the bulk of the printing plate 1 suchthat the U-shaped patterning cavity 17 is bridged and that the twostrings of cavities remain isolated from each other.

The openings of the patterning cavities 12, 13, and 17 represent apattern to be transferred and are all arranged in the transfer region10.

FIG. 1C schematically illustrates a state during a first step of apattern transfer process: A substrate 2 is brought into conformalcontact with the transfer region 10 of the printing plate 1. Thesubstrate 2 closes the openings of the two strings of cavities such thatthe first string of cavity becomes a first conduit and the second stringof cavities becomes a second conduit.

A first fluid 31 is filled into the first service cavity 15 and flowsunder the influence of gravity and capillary forces through theconnected patterning cavities 12 and 13 and the link cavity 14 to thesecond service cavity 16. The continuous flow has the advantage toimprove the homogeneity of the fluid composition within the firstconduit as well as during the course of the following reaction with thesubstrate 2. A second fluid 32 is filled correspondingly into the thirdservice cavity 18 and flows through the U-shaped patterning cavity 17 tothe fourth service cavity 19.

Surface 3 of the substrate 2 is hereby brought into contact with thefluids 31 and 32 at the positions of the patterning cavities 12, 13, and17. Hence the fluids 31 and 32 can thereby interact with surface 3 ofsubstrate 2. The interaction can be of various kinds. Materialdeposition as well as material removal can take place.

FIG. 2 schematically shows an arrangement which is particularly suitedfor rinsing larger quantities of the different fluids 31 and 32subsequently e.g. through the second conduit. The two service cavities18 and 19 are connected to a fluid supply means 4 consisting of a pump41, connecting tubes 44, 45, 46 and two reservoirs 42 and 43 filled withthe fluids 31 and 32, respectively. A manually or otherwise operablecock 47 provides the possibility to pump the fluids 31 and 32 from thereservoirs 42 and 43 in alternation through the connected cavities 17,18, and 19.

This arrangement allows performance of a series of processing steps atthe contacted substrate surface. It is possible, e.g., to depositalternating layers of two different materials, forming a superlattice onsurface 3 without removal of the printing plate 1 from the substrate 2.One also might use an etchant as the first fluid 31 and first etch agroove into the contacted substrate surface 3 and then refill it in asecond step with a different material, represented by the second fluid32. In this example, the fluid supply means 4 is external. It also ispossible, as an alternative or even additionally, to integrate the fluidsupply means 4 or part of it into the printing plate 1, for instance byemploying micromechanic techniques for its fabrication. Also a cleaningor neutralizing fluid can be used as one of the fluids 31 and 32. Thenumber of fluids which can be used is generally not restricted, but canbe any suitable number. Hence, various subsequent process steps can beperformed without removing substrate 2 from printing plate 1, such thatthe precision on surface 3 of the achieved substrate modificationremains constant. In the same way, the number of independent conduits isnot limited and can be chosen according to the desired pattern.

FIGS. 3A-3G show different states in a process of surface modificationwhich is possible with the arrangements depicted in FIGS. 1A, 1A, 1C and2. The conduits are represented in the cross-sectional view exemplarilyby the two separated patterning cavities 12, 17, located in the transferregion 10 of the printing plate 1. Their openings are sealedhermetically by surface 3 of substrate 2 which is in conformal contactwith printing plate 1.

FIG. 3A shows an arrangement, just after surface 3 of substrate 2 wasplaced on top of the printing plate 1. The patterning cavities 17, 12are empty. The cross-section of the U-shaped patterning cavity 17 islarger at the base of the U-shaped patterning cavity 17 which is locatedfar away from the surface in order to allow a more effective fluidtransport in spite of the smaller opening located directly near thesubstrate surface. The cross-section of the first patterning cavity 12is a rectangle since the opening of this cavity 12 is in this examplesufficiently wide.

FIG. 3B shows the effect of rinsing the two different fluids 31 and 32through the patterning cavities 12 and 17. The first fluid 31 is chosento contain material that is to be deposited on surface 3 of substrate 2.Hence, a layer 21 of a material begins to precipitate and adheres in thearea of the contacted substrate surface 3 exposed to the first fluid 31,forming layer or elevation 21. The second fluid 32 is an etchant. Hence,a depression 22 is being formed or etched into surface 3 where the areais exposed to second fluid 32.

FIG. 3C shows the resulting pattern on the contacted substrate surface 3if the patterning process is terminated at this stage and the substrate2 is separated from printing plate 1. The pattern consists of layer orelevation 21 and depression 22.

FIG. 3D shows, as an alternative, a possible second processing step: Thefluids 31, 32 are subsequently replaced by another couple of fluids 33,34 out of which a first deposited element 23 and a second depositedelement 24 are precipitating onto the contacted substrate surface 3. Thefigure depicts a situation where the second deposited element 24 hasjust refilled depression 22.

FIG. 3E shows the resulting pattern on surface 3 of substrate 2 afterremoval of the printing plate 1.

FIG. 3F shows how patterned substrate 2 may be used as a secondarypattern-transfer device. For this purpose, substrate 2 which here isused as an intermediate substrate is placed on top of a target substrate5 such that conformal contact is made with the first deposited element23.

FIG. 3G shows the target substrate 5 after removal of the intermediatesubstrate 2. It is assumed here that the adhesive force between thefirst deposited element 23 and layer or elevation 21 is weaker than thatbetween first deposited element 23 and surface 6 of target substrate 5.It also is assumed that the adhesive force between the first depositedelement 23 and layer or elevation 21 does not exceed the cohesive forceswithin first deposited element 23. As a result, first deposited element23 is transferred to target substrate 5 as a whole.

The described two-step pattern transfer process significantly widens thescope of feasible substrate modifications. It is possible, for instance,to employ as fluids 31 and 32 for the first steps (FIGS. 3B and 3C)fluid materials which are too reactive for a direct exposure to thetarget substrate 5. It further may be possible to achieve orientedprecipitation of the constituents of the first deposited element 23 byan adequate choice of the material of layer or elevation 21. Withappropriate precautions, the orientation may be maintained during thetransfer to intermediate substrate 5 such that the constituents may getattached "backside up" to intermediate substrate 5.

Oriented deposition is also a topic described by H. Biebuyck, E.Delamarche and B.Michel in the International patent applicationPCT/IB96/00908. It occurs, for instance, with layers of self-assemblingmolecules with the help of such a two-step process, the molecules couldbe made to adhere to a substrate surface in an orientation which wouldnot be possible in a straight-forward self-assembly process.

FIGS. 4A-4C illustrate how the pattern transfer can be controlled by anexternal physical influence which here is electrolytic dissolution byapplication of an electric field to selected cavities.

For this purpose, the printing plate 1 comprises an insulating transferelement 60 and an electrically conductive bottom element 70. Patterningcavities 61 and 62 are cut into the transfer region 10 of the printingplate 1 in such a way that transfer element 60 forms the side walls ofthe patterning cavities 61 and 62 and the bottom element 70 forms theircommon bottom. Bottom element 70 is composed of a first electricallyconductive segment 71 and a second electrically conductive segment 72.An insulating layer 73 isolates them against each other. A voltage U canbe applied to the different patterning cavities 61 and 62 individuallyby closing one or several switches 81 and 82. Substrate 2, assumed to beconductive, acts as a counterelectrode here.

FIG. 4A shows the arrangement, just after substrate 2 was placed on topof printing plate 1.

FIG. 4B shows the effect of applying a voltage between the secondsegment 72 and substrate 2 while first fluid 31 is rinsed through bothpatterning cavities 61 and 62. Due to electrolytic dissolution whichonly takes place where the electronic voltage U is present, thedepression 22 is etched into the exposed area of the contacted substratesurface at the position juxtaposed to the patterning cavity 62. Thesubstrate area juxtaposed to patterning cavity 61, however, remainsunmodified. This example is to show that a substrate modification can beachieved by introducing control via a physical or chemical or, moregenerally environmental dependence. For instance, a magnetic, pressure,optical, catalytic, etc. control can be achieved by modifying thearrangement accordingly. Also, combinations of such control mechanismscan be used.

FIG. 4C shows the pattern resulting from this process, which consists ofthe depression 22 in substrate 2 in this case.

FIGS. 5A-5C show a biotechnological application of the arrangementsdepicted in FIGS. 1A-1C and 2 and the method illustrated in FIGS. 3A-3G,namely the preparation and application of the substrate 2 as a testslide for chemically defined bodies. For this purpose, test slide 2 iscoated with an attachment means 25 which exerts an orienting effect onthe respective complementary chemically defined bodies 56, 57, and 58besides enhancing their adhesion.

FIG. 5A shows a state in a process of pattern formation while theprinting plate 1 and substrate 2 are in conformal contact. The conduitsare represented in cross-sectional view by three patterning cavities126, 127, and 128 which belong to different conduits. The conduits arefilled with different fluids 36, 37, and 38 which contain thecomplementary chemically defined bodies 56, 57, and 58, respectively.

FIG. 5B shows substrate 2 after removal from printing plate 1. Threeseparated complementary chemically defined body layers 26, 27, and 28are deposited upon the attachment means 25, layers 26, 27, and 28consist of complementary chemically defined bodies 56, 57, and 58,respectively.

FIG. 5C shows the use of substrate 2 as a test slide. Substrate 2 isimmersed into a test fluid 61 in a container 6. Test fluid 61 is to beanalyzed for the occurrence of chemically defined bodies 66, 67, and 68which will adhere selectively to complementary chemically defined bodies56, 57, and 58, i.e. the layers 26, 27, and 28, respectively. In thesituation depicted in FIG. 5C, a few of the chemically defined bodies 66and 68 have settled on top of layers 26 and 28 of complementarychemically defined bodies 56 and 58 already, but not on the middle layer27 of complementary chemically defined bodies 57, since chemicallydefined bodies 57 therefor are missing in test fluid 61.

FIG. 5D shows the test slide 2 after removal from container 6 and testfluid 61. Chemically defined bodies 66 and 68 have formed monolayers 76and 78 on top of layers 26 and 28 of complementary chemically definedbodies 56 and 58. Middle layer 27 of complementary chemically definedbodies 57 is uncovered, indicating that corresponding chemically definedbody 67 was missing in test fluid 61. The presence of the layers 76 and78 of the chemically defined bodies 76 and 78 can be readily tested, forinstance by attaching fluorescent labels to complementary chemicallydefined bodies 56, 57, and 58 the fluorescence of which gets quenched bythe adhering chemically defined bodies 76, 77, and 78. Thus, here, whenilluminated with UV-light 81, only middle layer 27 shines up influorescence 82. Another possibility is the detection of fluorescenceemanating from chemically defined bodies 76, 77, and 78. Any other testis as well applicable, such as testing for electrical, magnetic or anyother physical or chemical property which is suited to distinguish ordetect attached chemically defined bodies 76, 77, 78.

The characteristic patterning structures of the pattern are preferablyof similar size as the structures used in microelectronics andmicrotechnology which in particular comprises structures with dimensionsin the 100 nm to 100 micrometer range. An embodiment with miniaturisedpatterning cavities, has the advantage that the pattern transfer processcan supplement or even replace the lithographic patterning processescommonly used in the fabrication of microelectronic or micromechanicdevices. It has the further advantage that very small quantities offluids are used up by the patterning process, which can be of particularimportance for biotechnological applications. The use of a miniaturisedconduit allows to guide, for instance, nanoliter quantities of reagentto targeted areas. This can be used to immobilize ligands, a first stepin many bioassays, on a substrate with sub micron control. Makingpatterns of ligands by chemical reactions within the conduits of thenetwork has several practical benefits. It is simple, inexpensive andhighly economic of reagents. It furthermore is compatible with manyexisting chemistries and substrates already employed for the attachmentof macromolecules to surfaces, and its use does not preclude newer formsof covalent coupling requiring light activation since the printing plateand/or substrate may be made from material transparent well into theultraviolet.

Using an elastomeric material, has the advantage that the transferregion of the patterning device can adapt to the shape of the contactedsubstrate surface by elastic deformation within large tolerances. Thepatterning device or at least part of it can be made, for instance, froman elastomer. This results in the advantage that the shape tolerancerequirements can be relaxed. As a further advantage, appropriateelastomers are transparent to optical radiation far into the UV regionof the spectrum, allowing for effective photoactivation and/orpassivation of materials contained in the fluids in the conduit.

Different link cavities may cross each other or patterning or servicecavities without getting into physical contact with them.

The flow direction within the conduits can be controlled also byadditional means such as vessels. It is also possible to integrate smallswitching elements which perform a switching of the fluid flow.

Additionally, adjustment means or alignment means can be provided whichensure the correct position of substrate 2 with respect to transferregion 10. Such alignment can be a passive one, such as matchingfeatures, e.g. notches and protrusions but can also be performed by anactive mechanism.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:
 1. A patterning device for creating apattern on a substrate comprising at least one patterning cavity havingan opening located at the surface of said patterning device within atransfer region, where said substrate during patterning comes intoconformal contact with said patterning device, at least one servicecavity located in a service region and connected to said patterningcavity, such that a patterning fluid is able to flow from said servicecavity to said patterning cavity, said patterning device furtherincluding a transfer element which forms the surface of said transferregion and at least part of the side walls of the patterning cavitiesand a bottom element which is made from a material different from thatof said transfer element.
 2. The patterning device according to claim 1,wherein the width of said opening at the surface of said patterningdevice of at least one patterning cavity is smaller than the width ofsaid respective patterning cavity below said opening.
 3. The patterningdevice according to claim 1, further including a fluid supply means forsupplying said patterning fluid to said service cavity.
 4. Thepatterning device according to claim 1, further including a secondservice cavity which is connected to said patterning cavity, such thatsaid patterning fluid is able to flow from said patterning cavity tosaid second service cavity.
 5. The patterning device according to claim1, wherein the surface inside said patterning cavity is wettable by saidpatterning fluid and the surface of the transfer region next to saidpatterning cavity is poorly wettable.
 6. The patterning device accordingto claim 1, wherein said transfer region lies in a recess of saidpatterning device.
 7. The patterning device according to claim 1,further including a plurality of said patterning cavities beingconnected by at least one link cavity embedded in said patterningdevice.